Description of the Prior Art
It has long been considered desirable to provide a floor covering having the characteristics of durable, hard surfaced ceramic tile and the resilience of softer floor coverings such as asphalt or vinyl floor coverings and carpeting. Until the advance of the subject invention, this combination of properties was unattainable.
In the past, it was found that ceramic tile, when set over a soft or low strength layer of material with conventional Portland Cement, dry-set or epoxy grout, was subject to breaking and chipping under ordinary use. See, for example, the discussion in U.S. Pat. No. 3,319,392 issued to John V. Fitzgerald.
The use of edge-bonded tile sheets having flexible material to bond the tile edge-to-edge is known. However, commercial installation of edge-bonded tile sheets requires setting of the edge-bonded tile sheets in strong non-resilient adhesive layers. Further, rigid support of edge-bonded tile sheets is required to avoid damaging the tile.
Efforts have also been made to provide a satisfactory floor covering for installing tile in thin layers over a waterproof membrane. In the past, tile set on a waterproof membrane tended to crack due to the fact that the membrane, in order to be effective, was required to be soft and flexible. Typically, a floor protected with a waterproof membrane could not be provided with a tile covering unless it was depressed one and one-half to two inches and then provided with a concrete or mortar layer over the flexible membrane. The concrete or mortar provided the rigid support necessary for the ceramic tile.